Neuromyelitis Optica (NMO)
What is neuromyelitis optica?
Neuromyelitis optica (NMO) is a rare chronic condition that affects your eyesight and your ability to move. It’s an autoimmune disorder, meaning it happens because your immune system mistakenly attacks parts of your central nervous system.
This condition has undergone name changes over the years. The condition’s original name, Devic’s disease, comes from Eugène Devic, the French neurologist who first described it. However, an international group of experts gave the condition its current name in 2015. This condition’s full, formal name is neuromyelitis optica spectrum disorder (NMOSD). But it’s still common for healthcare providers and other experts to simply call it neuromyelitis optica.
Experts previously thought that NMO was a rare type of multiple sclerosis (MS). However, they know now that it’s a separate condition.
Who does neuromyelitis optica affect?
NMO is much more likely to affect women and people assigned female at birth, who make up about 80% to 90% of cases. It usually affects people between the ages of 30 and 40. NMO in children is very uncommon, making up only 5% or so of cases.
People of all races and ethnic backgrounds can develop NMO, but it doesn’t affect people of all backgrounds at the same rates. NMO affects people of African descent, especially African Caribbean descent, at higher rates. The Caribbean island of Martinique, a French territory, has the highest number of cases for the size of its population, about 10 per 1000,000 people. It can also disproportionately affect people of Asian descent.
How common is neuromyelitis optica?
NMO overall is rare. The average number of people with NMO per 100,000 is between 0.3 and 4.4. That means there are between 1,000 and 14,600 cases in the United States and between 24,000 and 350,600 cases worldwide.
How does neuromyelitis optica affect my body?
To understand how NMO affects you, it helps to know a little about the makeup of your nervous system. Your nervous system consists of your brain and spinal cord (the optic nerves, which are the cranial nerves that allow you to see, are technically part of your brain also).
Together, your brain and spinal cord are known as the central nervous system. The network of nerves that branch outward throughout your entire body makes up your peripheral nervous system.
Your nervous system transmits information to and from your brain using chemical and electrical signals. Those signals travel through specialized cells known as neurons, which form incredibly complex connections to other neurons around them.
A key part of every neuron is an arm-like extension called the axon, which carries electrical signals to the synapses (pronounced sin-apps-is) at the end of the axon. These finger-like extensions are where the electrical signals in the neuron become chemical signals. The synapses connect and communicate with other nearby neurons.
Around the axon, there’s a thin, protective coating called myelin, which is made up of fatty chemical compounds. Myelin helps with conduction of electrical signals along the axon and protects it from damage. NMO is a demyelinating disease, meaning it involves the myelin coating of the axon. Without the protective myelin coating, the axon is vulnerable to damage and deterioration.
Damage from NMO tends to involve neurons in two specific areas: The optic nerve that connects your eyes to your brain, and your spinal cord, which is the central connection point for nerve signals to reach before heading to your brain. NMO can affect your spinal cord at different levels, and every nerve that connects to your spinal cord below the affected area of your spinal cord can show the effects.
Symptoms and Causes
What are the symptoms of neuromyelitis optica?
NMO causes symptom “attacks,” meaning that the symptoms come and go. Attacks can last for days to months at a time. These attacks are often severe and can sometimes cause permanent damage. When this happens, the effects might be permanent even after an attack ends.
The symptoms of NMO break down into three categories (with more about these categories below):
- Optic neuritis. These symptoms happen because of inflammation of one or both of your optic nerves.
- Myelitis. These symptoms happen because of spinal cord inflammation.
- Brain function disruptions. These happen when NMO affects your hypothalamus or your brainstem, which are key structures that control automatic processes in your body.
Your eyes pick up light from the world around you and send signals through the optic nerve, the connection between your eyes and brain. Your brain then processes those signals, giving you your sense of sight.
Optic neuritis causes inflammation of the optic nerve, causing it to swell. There isn’t much space in that area of your head, so that swelling may put too much pressure on your optic nerve. Lying on an arm or leg can interrupt signals from your sense of touch, causing pain, tingling and numbness in the affected body part. Pressure on your optic nerve has a similar effect on your eyes.
The symptoms of optic neuritis can affect one or both eyes, and the timing of the symptoms can affect one eye after the other or both at the same time. The symptoms include:
- Eye pain. This usually happens or gets worse when you move the affected eye(s).
- Blurred vision. This symptom may get worse when you’re physically active.
- Partial vision loss or blindness. You may lose all or part of your vision in one eye (an example of this is loss of the center of your field of vision). It can also cause dimming of your vision or trouble seeing colors.
- Trouble seeing in low light. This can make it difficult to do certain things at night, such as driving.
Myelitis is inflammation of your spinal cord. That inflammation can cause swelling, which puts pressure on your spinal cord or the nearby spinal nerves. That can partially or totally block nerve signals that try to pass through the affected area. When myelitis disrupts all types of nerve signals, it’s known as transverse myelitis.
The symptoms of myelitis depend on where the swelling is and what parts of your spinal cord or spinal nerves it affects. If the swelling puts pressure on spinal nerves, the symptoms will affect areas that rely on those nerves to connect to your brain. If it puts pressure on your spinal cord, the symptoms will affect all parts of your body with spinal nerve connections below the area of pressure.
The symptoms of myelitis include:
- Muscle weakness or paralysis. This affects body parts below the affected area of your spinal cord and/or farther down from the affected spinal nerves. This can cause trouble using your arms and hands or issues with walking or standing. If myelitis happens in your cervical spinal cord (the part of the spinal cord in the back of your neck), it can cause paralysis or weakness in muscles that control breathing, which can be deadly.
- Spasticity. This happens when a lack of control signals from your brain causes your muscles to act on their own. This then causes muscles to flex or tighten uncontrollably.
- Pain. Pressure on your spinal cord from myelitis can cause pain. The pain may happen because of the swelling itself or because the swelling causes affected nerves to send pain signals mistakenly.
- Incontinence. Myelitis can disrupt the nerve signals that give you control over your bladder and bowels, which is how you can control when you pee (urinate) or poop (defecate). Being unable to control those muscles can cause urinary incontinence or bowel incontinence.
- Sexual dysfunction. Myelitis can disrupt the nerve signals that control sexual functions or organs in your body.
Brain function disruptions
While it’s common for multiple sclerosis (MS) to cause changes in your brain, it’s less common for this to happen with NMO. When it happens, it can disrupt how your brain handles certain processes in your body. If these disruptions happen in your hypothalamus or brainstem, they can cause severe or even dangerous problems.
The brainstem is the lowest section of your brain, found at the lower back of your skull. This section is critical for two reasons: It links your brain and spinal cord, and it controls autonomic processes. Your body’s autonomic processes are the functions that happen without you thinking about them (automatic). Examples include breathing, blood pressure, sweating and more.
If NMO affects your brainstem, it can cause the following symptoms:
- Uncontrollable hiccups.
- Uncontrollable itching (pruritus).
- Nausea and vomiting that happen without a clear reason.
- Hearing loss.
- Double vision (diplopia), uncontrollable eye movements (nystagmus) or other problems with control of your eye movements.
- Facial paralysis (palsy).
- Dizziness or spinning sensation (vertigo).
- Difficulty with balance or coordination (ataxia).
- Nerve-based pain that you feel in your face (trigeminal neuralgia).
Just above the brainstem is your hypothalamus. This structure also handles automatic body processes. When NMO affects it, this can cause other body systems to malfunction. A key example of this is NMO with narcolepsy symptoms (such as excessive daytime sleepiness).
What causes neuromyelitis optica?
So far, experts can only partly explain how or why NMO happens. The reasons they know about or suspect include:
- Immune system malfunctions.
- Other autoimmune or inflammatory conditions.
Immune system malfunctions
NMO is an autoimmune condition, which means it happens when your immune system mistakenly attacks part of your own body. In this case, it attacks your optic nerves and/or your spinal cord.
There are two known autoimmune forms of NMO:
- Aquaporin-4 (AQP4) antibodies. AQP4 is a protein on the surface of certain nervous system cells. Its job is to move water in and out of cells. AQP4 antibodies mistakenly tell your immune system to attack this protein, damaging the cells that carry it on their surface. More than 80% of people with NMO have AQP4 antibodies in their blood.
- Myelin oligodendrocyte glycoprotein (MOG) antibodies. MOG is a protein that helps form and maintain the myelin coating on neurons. MOG antibodies mistakenly tell your immune system to attack this protein, which disrupts the myelin coating on your neurons. About 6.5% of people with NMO have this antibody in their blood.
These immune system malfunctions happen for mostly unknown reasons. However, there's data that suggests these malfunctions can happen after having an infection. About 15% to 35% of people who develop NMO had some kind of infection just before they developed NMO symptoms. However, more study is necessary to confirm this.
Currently, experts don’t know why NMO happens in people who don’t have AQP4 or MOG antibodies, who make up about 13.5% of those with this condition. They classify these cases as “idiopathic,” meaning they happen for unknown reasons.
Additionally, some experts believe NMO that involves MOG antibodies is actually a separate disorder. However, more research is necessary on this and that formal recognition, as a separate disorder has yet to happen.
Other autoimmune or inflammatory conditions
While NMO can happen on its own, it’s more likely to happen in people with other autoimmune or inflammatory conditions. However, more research is necessary before researchers can say whether or not these conditions can cause or contribute to NMO.
These conditions include:
- Lupus (systemic lupus erythematosus).
- Celiac disease.
- Sjögren’s syndrome.
- Myasthenia gravis.
- Antiphospholipid syndrome.
Experts suspect that genetic factors can play a role in NMO. One reason they suspect this is because this condition is more common in people of certain ethnicities or racial backgrounds. Another reason is that about 3% of NMO cases involve people in the same families. While they don’t have evidence that NMO is a condition you can inherit, there might be genetic factors that make it easier to develop NMO.
Can neuromyelitis optica spread from person to person?
Currently, there’s no evidence that NMOSD (NMO) can spread from person to person.
Diagnosis and Tests
How is neuromyelitis optica diagnosed?
One of the most important differences between multiple sclerosis (MS) and NMO is that some test methods can confirm if a person has it. A healthcare provider can diagnose NMO using a combination of the following:
- Blood tests. One of the most important tools for healthcare providers to diagnose NMO is testing your blood for AQP4 or MOG antibodies. While blood testing can’t always confirm NMO — because about 13.5% of cases don’t involve identifiable antibodies — it’s still useful for diagnosing this condition.
- Magnetic resonance imaging (MRI) scans. MRI scans are especially helpful in identifying NMO. This condition causes changes to your spinal cord and other parts of your central nervous system that an MRI scan can detect. These are usually distinct enough from changes seen with MS for healthcare providers to tell them apart and rule out MS.
- Physical and neurological examinations. These tests look for signs and symptoms that can happen because of NMO. The neurological exam is especially important because it can identify problems with your senses, reflexes, muscle movements, balance and facial functions.
- Personal and medical history. This involves your healthcare provider asking questions about your health, symptoms, and personal and medical history details.
Other tests are also possible, as your healthcare provider may feel it’s important to rule out other conditions. Your provider can tell you more about the tests they recommend and why they recommend those tests.
Management and Treatment
How is neuromyelitis optica treated, and is there a cure?
NMO isn’t curable, but thanks to continuing research, this condition is treatable. Because NMO is an autoimmune condition, the main treatments take two forms: acute treatment and long-term management.
- Acute treatment: This focuses on treating the immediate effects of an NMO attack, especially inflammation. Corticosteroids (or other kinds of prescription anti-inflammatory drugs) are most common for this. Acute treatment is extremely important, as it reduces the risk of permanent damage from an attack.
- Long-term management: NMO happens because your immune system mistakenly attacks your nervous system. Managing that involves suppressing or modulating your immune system, which minimizes its ability to damage your nervous system. This can prevent NMO attacks or at least limit how severe they are or how long they last. Experts recommend these treatments for people with and without AQP4 antibodies.
What medications or treatments are used?
There are several drugs and treatments that can help treat NMO, including:
- Anti-inflammatory drugs: These drugs reduce the inflammation of your nervous system. The most common drugs that do this are corticosteroids, such as prednisone. It’s common for healthcare providers to start these medications in intravenous (IV) form, infusing them into your bloodstream. The use of IV drugs happens during treatment in a hospital. After you leave the hospital, your provider may switch you to similar drugs that you take in pill form by mouth.
- Plasma exchange (plasmapheresis): When steroids aren’t helpful, your healthcare provider may recommend a procedure called plasma exchange. This procedure removes blood plasma from your body and replaces it with a matching amount of donor plasma. Swapping out some of your plasma for donor plasma removes some of the immune cells and chemical markers (which strengthen your immune response) circulating in the plasma. That helps reduce your body’s immune response, which reduces inflammation.
- Intravenous immunoglobulin (IVIG): This procedure involves infusing plasma into your body through an IV. The plasma you receive contains immunoglobulin (pronounced “im-yew-no-glob-yew-lin”), which is plasma that contains donor antibodies, which won’t attack your immune system as your own immune system will.
- Immune-suppressing drugs (immunosuppressants): These are medications you take regularly. Some you receive in IV form, which happens at an infusion clinic or similar medical facility. Others come in a pill form that you can take at home. Most people will take these pills for years or even indefinitely.
What are the possible complications or side effects of the treatments?
The side effects of the possible treatments can depend on many factors, including the specific drug, the severity of your condition and your medical history. However, one side effect of immune-suppressing drugs stands out: They lower your immune response.
Your immune system protects you from outside invaders like viruses, bacteria, fungi and parasites. It also controls and puts a stop to cells behaving badly. If cells in your body malfunction, your immune system’s job is to step in and destroy them (cancer is when cells malfunction and disguise themselves from your immune system, allowing them to reproduce uncontrollably without drawing your immune system’s attention).
Taking immune-suppressing drugs can help prevent NMO attacks, but it also reduces your body’s ability to fight certain infections, and it can raise your risk of certain types of tumors (both cancerous and noncancerous). If you take immune-suppressing drugs, you’ll need to take certain precautions to lower your risk of getting sick. You also may need certain vaccinations to prevent or limit the severity of infectious diseases, like COVID-19, influenza (flu) or pneumonia, which can be severe and potentially deadly if you have a suppressed immune system.
How soon after treatment will I feel better, and how long will it take me to recover from treatment?
The treatment and recovery timeline can vary with NMO because many factors play a role. Your healthcare provider is the best source of information on this. They can tell you the timeline that’s most likely in your case, and what you can do to help that process.
How can I reduce my risk of developing neuromyelitis optica, and is it preventable?
NMO happens unpredictably and for reasons that healthcare providers still don’t fully understand. Because of this, there’s no way to prevent it or reduce your risk of developing it.
Outlook / Prognosis
What can I expect if I have neuromyelitis optica?
If you have NMO, you can expect this condition to start without much warning. Some people have a respiratory infection or other kinds of illnesses just before developing it, but this only happens in about one-third (or less) of cases.
NMO attacks will cause vision problems, as they affect your optic nerves. That causes eye pain and disruptions in your vision. These usually get worse over a few days or weeks before peaking. These symptoms can be permanent if there’s significant damage to your optic nerves, but treatment can help avoid permanent damage.
NMO also affects the bottom-most area of your brain — the brainstem — and your spinal cord. That can cause automatic body processes to malfunction, leading to nausea and vomiting, uncontrollable hiccups and more.
When myelitis is severe, the pressure on your spinal cord can disrupt nerve signals to every part of your body at or below the affected area. That can cause muscle weakness, paralysis, loss of the sense of touch below a certain point and more. This can be severe if paralysis or muscle weakness affects muscles that control breathing. Quick treatment may keep these effects from becoming permanent.
NMO is an autoimmune condition, meaning it happens because your immune system mistakenly attacks parts of your own body. In this case, your immune system targets your nervous system. Treatment for this condition typically involves long-term suppression of your immune system. Unfortunately, that has the side effect of putting you at risk for infections. People who take immune-suppressing drugs need to take precautions to lower their risk of getting sick.
How long does neuromyelitis optica last?
NMO causes attacks, which are flare-ups of symptoms. For people with AQP4 or MOG antibodies, NMO is a lifelong condition. Currently, people with this disorder often need to take immune-suppressing drugs for years or the rest of their lives to avoid attacks.
About 10% to 20% of people with NMO will have only one attack and never have another. This is most likely in people who don’t have AQP4 or MOG antibodies. However, there’s no way to predict this with total certainty, so your healthcare provider may still recommend taking these drugs to reduce the risk of having an attack.
What’s the outlook for neuromyelitis optica?
In years past, NMO was a condition that had a very negative outlook. However, experts now know NMO is treatable, thanks to discoveries into the immune origins of this condition. Medications to manage this condition reduce the relapse rate by between 72% and 88%. The five-year survival rate for this condition is between 91% and 98%.
For people with NMO who experience multiple attacks, this condition is more likely to cause the loss of certain abilities, such as vision and movement. About 22% of people will fully recover from the effects of NMO, getting back all of their abilities. About 7% won’t recover at all. The remaining 71% will recover at least partly but may experience lingering effects.
How do I take care of myself?
NMO is manageable, and your healthcare provider will help guide you on how to take care of yourself. Some of the most important things you can do include:
- Take your medication. Whether you’re recovering from an NMO attack or have gone for a long time without one, it’s essential to take your medication as prescribed. Medications can prevent or reduce damage from an ongoing attack and can reduce the risk of future attacks. You shouldn’t stop taking these medications unless you talk to your provider first.
- See your provider as recommended. Follow-up visits are key with NMO so your healthcare provider can monitor the effects of this condition. Routine blood testing is common with NMO, showing your provider how active your immune system is. That allows them to adjust your medications(s) if necessary.
- Take precautions to avoid getting sick. If you take immune-suppressing medications, that lowers your immune system’s ability to attack your nervous system. Unfortunately, it also can lower your immune system’s ability to fight contagious illnesses like the common cold, the flu, COVID-19, pneumonia and urinary tract infections (UTIs). Wash your hands often (either with soap and water or with alcohol-based hand sanitizer). Your healthcare provider may also recommend wearing a mask in public or other precautions, depending on your overall risks.
When should I call my healthcare provider?
People taking immune-suppressing drugs have a higher risk of getting sicker from common infections, even ones that aren’t serious under ordinary circumstances. For someone taking immunosuppressants, you should call your healthcare provider if you have any of the following symptoms:
- Severe fatigue (feeling unusually tired or exhausted) or weakness.
- Nausea and vomiting.
- Unexpected weight changes.
- Urinating more often than usual, feeling lower back pain, or pain or burning while urinating (these are signs of a urinary tract infection).
- Symptoms of upper respiratory infections, such as coughing, sneezing, runny nose or sore throat.
- Other signs of infection, such as fever, chills and muscle aches.
Frequently Asked Questions
What’s the difference between neuromyelitis optica vs. multiple sclerosis?
NMO and multiple sclerosis (MS) are conditions that have many similarities and overlapping symptoms. For years, experts mistakenly thought that NMO was a type of MS. But researchers now know that these are separate conditions.
A key difference between NMO and MS is that lab testing can help detect antibodies that cause NMO (though it can’t detect antibodies in all cases). The treatments for NMO and MS are also different, and some treatments for MS can make NMO symptoms worse.
A note from Cleveland Clinic
Neuromyelitis optica (NMO) is a rare chronic disease that happens when your immune system attacks specific parts of your central nervous system. Experts previously thought this was a rare type of multiple sclerosis (MS) but now recognize it’s a separate condition. Unlike MS, lab testing can confirm most cases of NMO, allowing providers to recognize and treat it early.
Thanks to advances in research and medical understanding, NMO is a treatable condition. Attacks of this condition are treatable with medications or certain types of infusion procedures. Medications can treat and manage this condition in those who test positive for certain antibodies. That means people with NMO can manage their condition better and reduce the risk of future attacks.
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